A cylindrical battery cell

Abstract

The present invention proposes a cylindrical battery cell, comprising a core package, a top cover and a coil spring; a pole lug group is provided on at least one axial end face of the core package; the top cover is provided at the end of the core package having the pole lug group; the coil spring is provided between the core package and the top cover; the coil spring is conical, one end of the coil spring is fixed on the top cover and the other end is in contact with the pole lug group; the top cover approaches the core package and squeezes the coil spring, so that the coil spring is compressed to the maximum, and the end of the coil spring fixed on the top cover also contacts the pole lug group; a coil spring is used instead of an adapter plate to be arranged between the pole post of the top cover and the full pole lug of the core package. When the top cover fits the battery cell shell, the coil spring will naturally deform due to pressure and fit on the full pole lug of the core package. The electricity is conducted to the electrode through the spring fitted on the full pole lug, so there is no need to weld the coil spring to the full pole lug, and there is no risk of generating welding slag or cold welding.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a cylindrical battery core. Background Art

[0002] Currently, cylindrical battery cells are made by coating copper and aluminum foil with electrode materials, then rolling and baking the copper and aluminum foils to form positive and negative electrode sheets. The tabs of the positive and negative electrode sheets are then flattened into fan-shaped tabs using a flattening machine. An adapter is then laser-welded to the tabs, and the other end of the adapter is laser-welded to the terminal post on the cell's top cover, allowing current to flow between the tabs and the post. Chinese patent CN113708017A discloses a battery adapter structure using an adapter.

[0003] The adapter needs to be welded twice, requiring two different welding machines, resulting in low welding efficiency. Furthermore, problems such as cold joints and tab cracks are very likely to occur during the welding process, which not only affects the cell's current capacity, but also the safety performance of the cell due to the debris generated during the welding process. The adapter also often heats up due to the excessive welding resistance. Summary of the Invention

[0004] In view of this, the present invention proposes a cylindrical battery cell to solve the problem that the adapter needs to be welded twice, and the welding process is very likely to cause cold welding and tab rupture, which will affect the current capacity of the battery cell.

[0005] The technical solution of the present invention is implemented as follows: the present invention provides a cylindrical battery cell, including a core package, at least one of whose axial end faces is provided with a tab group; a top cover, provided on the end of the core package having the tab group; a coil spring, provided between the core package and the top cover; wherein the coil spring is conical, one end of the coil spring is fixed on the top cover and the other end is in contact with the tab group; the top cover approaches the core package and squeezes the coil spring, so that the coil spring is compressed to the maximum, and the end of the coil spring fixed on the top cover also contacts the tab group.

[0006] On the basis of the above technical solution, preferably, it further includes an adapter ring, which is arranged between the core package and the top cover; wherein the adapter ring is simultaneously overlapped on each tab group; and one end of the coil spring away from the top cover is fixed to the adapter ring.

[0007] More preferably, the inner diameter of the end of the coil spring fixed to the top cover is smaller than the inner diameter of the end of the coil spring away from the top cover.

[0008] More preferably, the inner diameter of the adapter ring is not less than the inner diameter of the end of the coil spring away from the top cover; when the coil spring is maximally compressed, the coil spring is located inside the adapter ring.

[0009] Based on the above technical solution, preferably, when the coil spring is maximally compressed, the helical line of the coil spring contacts at least one lug group.

[0010] More preferably, when the coil spring is maximally compressed, the helical wires of the coil spring abut against each other.

[0011] More preferably, when the coil spring is maximally compressed, gaps are left between the coils of the coil spring.

[0012] Based on the above technical solution, preferably, the cross-sectional shape of the helical line of the helical spring is elliptical or rectangular.

[0013] On the basis of the above technical solution, preferably, it further includes a collecting plate, which is arranged between the core package and the top cover; wherein each tab group is welded to the collecting plate; and a coil spring is arranged between the collecting plate and the top cover, and the end of the coil spring away from the top cover is in contact with the collecting plate.

[0014] On the basis of the above technical solution, preferably, a protrusion is provided at the center of the end surface of the top cover facing the core package; one end of the coil spring is fixed on the protrusion.

[0015] The cylindrical battery cell of the present invention has the following advantages over the prior art:

[0016] The present invention uses a coil spring instead of an adapter plate and is arranged between the pole of the top cover and the full pole ear of the core package. When the top cover is fitted to the battery cell shell, the coil spring will naturally deform due to pressure and fit on the full pole ear of the core package. The electricity is conducted to the electrode through the spring fitted on the full pole ear. Therefore, there is no need to weld the coil spring to the full pole ear, and there is no risk of generating welding slag or cold welding. The production efficiency is high and the cost is saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A three-dimensional diagram of a cylindrical battery cell of the present invention;

[0019] Figure 2 A perspective view of another embodiment of a cylindrical battery cell of the present invention;

[0020] Figure 3 It is a partial front view of the cylindrical battery cell of the present invention;

[0021] Figure 4It is a partial front view of another embodiment of the cylindrical battery cell of the present invention;

[0022] Figure 5 A perspective view of a coil spring according to the present invention;

[0023] Figure 6 A perspective view of another embodiment of a coil spring of the present invention;

[0024] Figure 7 A top view of the coil spring of the present invention in a maximum compression state;

[0025] Figure 8 A top view of another embodiment of the coil spring of the present invention in a maximum compression state;

[0026] Figure 9 A top view of another embodiment of the coil spring of the present invention in a maximum compression state;

[0027] Figure 10 This is a top view of a coil spring in a maximum compression state according to another embodiment of the present invention.

[0028] In the figure: 1, core package; 11, tab group; 2, top cover; 21, protrusion; 3, coil spring; 301, gap; 4, adapter ring; 5, collecting plate. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] Example 1:

[0031] like Figure 1 As shown, combined Figure 2 and Figure 3 A cylindrical battery cell of the present invention includes a core package 1, a top cover 2 and a coil spring 3.

[0032] Among them, a tab group 11 is provided on at least one end face of the core pack 1 in the axial direction. The two ends of the core pack 1 are the positive and negative poles of the battery cell, respectively, so both have full tabs. The full tabs are composed of several fan-shaped tab groups 11 formed by flattening the positive and negative electrode sheets through a flattening device. The core pack 1 is set in the battery cell shell.

[0033] The two top covers 2 are respectively placed at the ends of the core pack 1 with the tab group 11. During assembly, the battery cell case is a cylindrical tube. The two top covers 2 are respectively attached to the two ends of the opening of the battery cell case and together with the case, they wrap the core pack 1; the edges of the top covers 2 are sealed together with the edges of the battery cell case, forming a sealed structure for the battery cell case.

[0034] The coil spring 3 is disposed between the core pack 1 and the top cover 2. In this embodiment, the coil spring 3 needs to be a conical spring because, when the coil spring 3 is compressed to its maximum, it needs to be deformed into a sheet-like structure to contact the tab assembly 11, thereby making the coil spring 3 act like a transition piece. If other types of springs, such as cylindrical springs, are used, their helical lines overlap, so after maximum compression, the helical lines will be pressed together, resulting in the spring still being thicker.

[0035] Specifically, one end of the coil spring 3 is fixed on the top cover 2 and the other end is in contact with the tab group 11; generally speaking, the top cover 2 will have a pole, which is used to connect the adapter plate, so the top cover 2 is provided with a protrusion 21 in the center of the end face facing the core package 1, so that one end of the coil spring 3 is fixed on the protrusion 21, and the end of the coil spring 3 can be directly welded to the protrusion 21, but in this case, in order to avoid the occurrence of cold welding or the generation of welding slag, the end of the coil spring 3 can be connected to the protrusion 21 through a clamping structure or a plug-in structure.

[0036] By adopting the above technical solution, when the top cover 2 approaches the core package 1, the coil spring 3 will be squeezed. When the top cover 2 is completely installed on the battery cell shell, the coil spring 3 can be compressed to the maximum. At this time, one end of the coil spring 3 fixed on the top cover 2 will also contact the tab group 11. Under ideal conditions, since the coil spring 3 reaches the maximum compression, its spiral line is completely on the same plane, so the entire spiral line of the coil spring 3 is also in close contact with the tab group 11, so that the coil spring 3 can be regarded as being compressed into a sheet-like body, and the end face of the sheet-like body is in contact with the tab group 11 of the full tab, thereby achieving the purpose of conducting the tab group 11 and the pole.

[0037] It should be noted that since the principle used in this case is to compress the coil spring 3 into a sheet-like body that contacts the entire pole ear to achieve conduction, the coil spring 3 can achieve the function of switching regardless of whether it adopts a conical cylinder with a small top and a large bottom, or an inverted conical cylinder with a large top and a small bottom. However, when the coil spring 3 is in the shape of an inverted cone, the radial width of the end of the coil spring 3 that contacts the entire pole ear is relatively small. On the one hand, it is difficult to ensure that the end of the coil spring 3 can contact as many pole ear groups 11 as possible. On the other hand, there is a hollow hole in the center of the cylindrical winding core. When the radial width of the end of the coil spring 3 is relatively small, the end of the coil spring 3 may be inserted into the hollow hole, which not only affects the contact effect of the coil spring 3 with the entire pole ear after compression, but may also cause damage to the cylindrical winding core. Moreover, the end of the coil spring 3 with a larger radial width is difficult to connect with the pole. Therefore, in order to enable the end of the coil spring 3 to be connected to the pole, the inner diameter of the end of the coil spring 3 fixed on the top cover 2 is smaller than the inner diameter of the end of the coil spring 3 away from the top cover 2, that is, the coil spring 3 in this embodiment adopts a cone shape with a small top and a large bottom.

[0038] Example 2:

[0039] On the basis of Example 1, although under ideal conditions, the entire spiral line of the coil spring 3 can contact the tab group 11 after being compressed, in fact, since the top cover 2 is close to the core package 1 to compress the coil spring 3, the end of the coil spring 3 is pressed by the protrusion 21 on the top cover 1, and the end of the coil spring 3 away from the top cover 2 abuts the tab group 11 on the end face of the core package 1. Therefore, after the coil spring 3 is compressed, the force points of the entire coil spring 3 are respectively on the end of the coil spring 3 away from the top cover 2 and the end of the coil spring 3 abutting the protrusion 21, while the force on the part of the spiral line between the two ends of the coil spring 3 is smaller. When the coil spring 3 is elastic, a height difference will be generated between the spiral lines of the coil spring 3, so that the part of the spiral line between the two ends of the coil spring 3 may not be in close contact with the tab group 11, which affects the effect of the coil spring 3 replacing the adapter plate to contact the entire tab.

[0040] In order to solve this problem and ensure the contact effect between the coil spring 3 and each tab group 11, as shown in FIG. Figure 1 As shown, combined Figure 10 , and also includes an adapter ring 4.

[0041] The adapter ring 4 is disposed between the core package 1 and the top cover 2; the adapter ring 4 is also overlapped on each tab group 11; and the end of the coil spring 3 away from the top cover 2 is fixed to the adapter ring 4. At this time, the function of the adapter ring 4 is to ensure that when the coil spring 3 abuts against the full tab on the end face of the core package 1, the adapter ring 4 can simultaneously contact each sector-shaped tab group 11. Therefore, when the coil spring 3 is maximally compressed, even if the middle portion of the spiral line of the coil spring 3 does not effectively contact the tab group 11, the adapter ring 4 at this time can be regarded as the outermost ring of the coil spring 3. As long as the adapter ring 4 is in contact with each tab group 11 at the same time, the conductive effect of the coil spring 3 will not be affected.

[0042] At the same time, to prevent the helical line of the coil spring 3 from overlapping with the adapter ring 4 after the coil spring 3 is compressed, the inner diameter of the adapter ring 4 is not less than the inner diameter of the end of the coil spring 3 away from the top cover 2. When the coil spring 3 is maximally compressed, the coil spring 3 is located within the adapter ring 4. It should be noted that the coil spring 3 in this case is a conical spring with a smaller top and a larger bottom.

[0043] In addition, although the adapter ring 4 is a complete ring in the figure of this embodiment, in fact, it can be directly ensured that the adapter ring 4 is in contact with each tab group 11 at the same time, so the adapter ring 4 can also be a gap ring.

[0044] Example 3:

[0045] Based on the first embodiment, since the coil spring 3 serves as a replacement for the adapter plate and the current collecting plate, in order to improve the efficiency of current conduction, under ideal conditions, the sheet-like body formed after the coil spring 3 is compressed to the maximum extent possible needs to contact all the terminal lug groups 11, so that each terminal lug group 11 can be electrically connected to the terminal post through the coil spring 3. To this end, the coils of the coil spring 3 need to be arranged as densely as possible, and the wire diameter of the coil spring 3 needs to be as small as possible, so that after the coil spring 3 is compressed to the maximum extent, there are as few gaps as possible between the coils, thereby preventing the coil spring 3 from failing to contact the terminal lug groups 11 located within the gaps between the coils.

[0046] Therefore, if Figure 1 As shown, combined Figure 8 and Figure 9 When the coil spring 3 is compressed to the maximum, the spiral lines of the coil spring 3 abut against each other. At this time, there is no gap between the spiral lines of the coil spring 3, so that the coil spring 3 can be regarded as a sheet-like integral structure when it is compressed to the maximum, thereby ensuring that the coil spring 3 can contact with all the tab groups 11 after maximum compression to achieve full tab conduction.

[0047] Example 4:

[0048] Based on the first embodiment, the third embodiment provides a coil spring 3 under ideal conditions. However, as described in the second embodiment, since a portion of the coil wire between the two ends of the coil spring 3 may not effectively contact the tab assembly 11, even without discussing whether the actual preparation of the coil spring 3 can meet the ideal requirements of the second embodiment, even after compression under ideal conditions, the coil wires of the coil spring 3 will still produce a height difference due to the elasticity of the coil spring 3, thus creating a gap between the coil wires. In this case, to avoid the adverse effects of the height difference between the coil wires when current is conducted, it is necessary to provide a gap between the coil wires of the coil spring 3, while eliminating contact between the coil spring 3 and a portion of the tab assembly 11.

[0049] Therefore, in contrast to the third embodiment, as another more realistic implementation method thereof, as Figure 1 As shown, combined Figure 7 When the coil spring 3 is compressed to the maximum, a gap 301 is left between the spiral lines of the coil spring 3, so that the coil spring 3 can be regarded as a structure similar to a mosquito coil when it is compressed to the maximum.

[0050] Embodiment 5:

[0051] On the basis of the first embodiment, as a specific implementation of the coil spring 3, as shown in FIG. Figure 1 As shown, combined Figure 6 The cross-sectional shape of the helical wire of coil spring 3 is elliptical. More precisely, the cross-sectional shape of the helical wire of coil spring 3 is circular, meaning that coil spring 3 is a round wire spring. It should be noted that to prevent the thick sheet-like structure formed by coil spring 3 after maximum compression from squeezing core package 1 and its tabs, the wire diameter of coil spring 3 is the same as the distance between top cover 2 and core package 1.

[0052] Example 6:

[0053] In Example 5, when the cross-sectional shape of the helical line of the coil spring 3 is circular, technicians found that although the coil spring 3 can be ideally regarded as a sheet structure after maximum compression, since the cross-sectional shape of the helical line of the coil spring 3 is circular, a number of continuous semicircular arc waves are actually formed on the end surface where the sheet formed by the coil spring 3 contacts the tab group 11. This results in that when the sheet formed by the coil spring 3 contacts the tab group 11, the crests of each semicircular arc wave make point contact with the tab group 11 rather than surface contact, and the part between the crests of adjacent semicircular arc waves does not contact the tab group 11. This point contact not only affects the contact effect between the coil spring 3 and the tab group 11, but also the part between the crests of adjacent semicircular arc waves will miss part of the tab group 11 and fail to achieve contact, thereby greatly affecting the conduction efficiency between the coil spring 3 and the entire tab.

[0054] In order to solve this problem, based on the first embodiment, compared with the fifth embodiment, as another specific implementation of the coil spring 3, as shown in FIG. Figure 1 As shown, combined Figure 5 , the cross-sectional shape of the helical wire of the coil spring 3 is a rectangle. More precisely, the cross-sectional shape of the helical wire of the coil spring 3 is a sheet-like rectangle, that is, the coil spring 3 is a spiral spring strip. In this embodiment, compared with the fifth embodiment, since the cross-sectional shape of the helical wire of the coil spring 3 is a sheet-like rectangle, in the sheet-like structure formed after the maximum compression of the coil spring 3, the helical wire of the coil spring 3 makes surface contact with the tab group 11 rather than point contact. This not only ensures the contact effect between the helical wire of the coil spring 3 and the tab group 11, but also ensures that part of the tab group 11 that may be missed in the point contact of the fifth embodiment can also make contact with the helical wire of the coil spring 3. Therefore, compared with the fifth embodiment, the conduction efficiency between the coil spring 3 and the entire tab is greatly improved.

[0055] It should also be noted that the principle of the present invention can essentially be regarded as cutting a thin sheet along a spiral trajectory, so that the thin sheet becomes a sheet-like spiral strip; when the sheet-like spiral strip is compressed, it returns to a sheet-like shape and contacts each tab group 11. At the same time, when the sheet-like spiral strip is relaxed and extended, it can maintain the conductive tab group 11 and the pole while leaving a larger gap between the top cover 2 and the core package 1; the principle of the present invention utilizes this phenomenon, so that the coil spring 3 can achieve conductive connection between the tab group 11 and the pole without welding to the tab group 11. Based on the above purpose, this embodiment better meets the preferred requirements of the present invention than the fifth embodiment.

[0056] In addition, in Example 5, when the cross-sectional shape of the helical wire of the coil spring 3 is elliptical, if the elliptical cross-sectional shape of the helical wire of the coil spring 3 is wide laterally and narrow vertically, it can actually be regarded as a leaf spring similar to the leaf spring of Example 6 to a certain extent. However, there is still the problem that the helical wire of the coil spring 3 is in point contact with the tab group 11 rather than surface contact, which will not be elaborated here.

[0057] Embodiment seven:

[0058] As mentioned above, when conducting current in existing cylindrical batteries, a current collecting plate 5 is usually required. After welding the current collecting plate 5 to the tab groups 11 of the full tab, the current collecting plate 5 is then connected to the poles on the top cover 2 through an adapter. During this process, a cold weld or welding slag will occur. However, the coil spring 3 of the first embodiment can replace the functions of the current collecting plate 5 and the adapter, and at the same time, there is no need to weld the coil spring 3 to the tab group 11, thereby avoiding the occurrence of cold welds or the generation of welding slag. Therefore, one of the advantages of this case over the existing technology is that it eliminates the use of the current collecting plate 5 and eliminates the problems caused by welding the current collecting plate 5 to the full tab.

[0059] However, as described in the previous embodiment, when the coil spring 3 is used to contact the tab group 11 for conduction, some tab groups 11 may not be able to contact the coil spring 3, thereby affecting the conduction efficiency between the pole of the top cover 2 and the entire tab.

[0060] Therefore, in actual implementation, when it is necessary to ensure that the full-tab tab group 11 is fully conductive with the pole on the top cover 2, in order to ensure that the full-tab tab group 11 can be conductive with the pole, as shown in FIG. Figure 1 As shown, combined Figure 4 , also includes a collecting plate 5.

[0061] The function of the collecting plate 5 is to ensure full power conduction. The collecting plate 5 is arranged between the core package 1 and the top cover 2 . Each tab group 11 is welded to the collecting plate 5 .

[0062] The coil spring 3 is disposed between the current collecting plate 5 and the top cover 2 . The end of the coil spring 3 away from the top cover 2 may only be in contact with the current collecting plate 5 or may be directly welded to the current collecting plate 5 .

[0063] When the core pack 1 is set in the battery cell shell, it will move forward, backward, left and right during use, which will also drive the collecting plate 5 to move relative to the top cover 2. At this time, due to the elastic ductility of the coil spring 3, the coil spring 3 can offset the tearing force caused by the movement of the collecting plate 5 relative to the top cover 2, thereby preventing the collecting plate 5 from separating from the pole.

[0064] Embodiment 8:

[0065] In the absence of technical conflicts, any combination of embodiments one to seven is also included.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cylindrical battery cell, characterized in that: include: The core package (1) has a tab group (11) provided on at least one axial end surface thereof; A top cover (2) is provided on one end of the core package (1) having the tab group (11); A coil spring (3) is arranged between the core package (1) and the top cover (2); The coil spring (3) is conical, one end of the coil spring (3) is fixed on the top cover (2) and the other end is in contact with the tab assembly (11); The top cover (2) approaches the core package (1) and squeezes the coil spring (3). When the coil spring (3) is compressed to the maximum, one end of the coil spring (3) fixed on the top cover (2) also contacts the tab group (11), and the spiral line of the coil spring (3) contacts the tab group (11), so that the coil spring (3) is deformed into a sheet-like adapter structure and contacts the tab group (11).

2. A cylindrical battery cell according to claim 1, characterized in that: Also includes: An adapter ring (4) is arranged between the core package (1) and the top cover (2); Wherein, the adapter ring (4) is simultaneously overlapped on each of the tab groups (11); One end of the coil spring (3) away from the top cover (2) is fixed to the adapter ring (4).

3. A cylindrical battery cell according to claim 2, characterized in that: The inner diameter of the coil spring (3) fixed to one end of the top cover (2) is smaller than the inner diameter of the end of the coil spring (3) away from the top cover (2).

4. The cylindrical battery cell according to claim 3, characterized in that: The inner diameter of the adapter ring (4) is not less than the inner diameter of the end of the coil spring (3) away from the top cover (2); When the coil spring (3) is compressed to the maximum, the coil spring (3) is located inside the adapter ring (4).

5. The cylindrical battery cell according to claim 1, characterized in that: When the coil spring (3) is compressed to the maximum, the spiral lines of the coil spring (3) abut against each other.

6. The cylindrical battery cell according to claim 1, characterized in that: When the coil spring (3) is compressed to the maximum, a gap (301) is left between the coils of the coil spring (3).

7. The cylindrical battery cell according to claim 1, characterized in that: The cross-sectional shape of the helical line of the helical spring (3) is elliptical or rectangular.

8. The cylindrical battery cell according to claim 1, characterized in that: Also includes: A current collecting plate (5) is arranged between the core package (1) and the top cover (2); Wherein, each of the tab groups (11) is welded on the current collecting plate (5); The coil spring (3) is arranged between the current collecting plate (5) and the top cover (2), and one end of the coil spring (3) away from the top cover (2) contacts the current collecting plate (5).

9. The cylindrical battery cell according to claim 1, characterized in that: The top cover (2) is provided with a protruding portion (21) at the center of the end surface facing the core package (1); One end of the coil spring (3) is fixed on the protruding portion (21).

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